Eleven years ago, I watched Steve Jobs unveil the iPod at Apple’s Cupertino, Calif., headquarters. The following week, I made my best prediction to date: that descendants of the iPod would replace the PC, as they are now doing. Gizmodo generously called it the best iPod prediction of all time. A colleague once suggested that I get it printed on my business cards.

Steve Jobs was a music fan to his core. I’ve been learning more about the depth of his musical appreciation as I prepare to teach a class about Apple and the music business this fall. One of his most formative experiences was watching a wheat field sway as he heard the music of Bach, imagining himself to be conducting the wheat. (He was on acid.) Jobs dated the folksinger Joan Baez for a spell, possibly because Bob Dylan, one of his heroes, had gone out with her. And his infamous attention to detail was motivated to an extent by a recording of the Beatles crafting their wonderful “Strawberry Fields Forever.” He said it showed how real, flawed humans could work and work on something until it was perfect.

The list goes on, but suffice it to say that music was a big part of Steve Jobs’ life. Moreover, it transformed the company he co-founded with Steve Wozniak from a struggling computer manufacturer into the most valuable company in the world, reinventing the music, software and telecommunications industries along the way.

If Apple had never delved into the world of music, it may never have made that transition; at the very least, it would have taken much longer. During that time, the world would have moved on. It might have been too late. Apple would not be the company it is today and may have faded into irrelevance or even worse.

Without music, Apple would not have . . .

. . . become so profitable.

When Jobs returned to Apple in late 1998, he simplified the company’s product line, eliminating projects like the Newton and narrowing Apple’s confusing array of computers to just a few key products. That was all about subtraction. The iPod was the first big addition following that period. As of today’s music-dominated keynote address, which ended with a Foo Fighters concert, Apple has sold over 350 million iPods. This not only made Apple extremely profitable but also helped it accrue a war chest that enabled it to expand into new markets.

. . . made Windows people switch to Macs.

It’s been said many times before, but it’s still worth mentioning: for many Windows users, the iPod was the first Apple product they ever experienced. Many of them loved their iPods so much that they thought, What else does Apple do this well? That so-called halo effect spread to Apple desktops, laptops, smart phones, set-top boxes and tablets. (The same is happening with Android-toting music fans, thanks to AirPlay.)

. . . become an entertainment powerhouse.

Without the iPod, there would be no need for iTunes. Without iTunes, Apple wouldn’t sell music, movies, television shows, e-books or apps. When this first deal to sell music online was made, little did the record labels know that the Mac-only iTunes, which could sell music to only around 4% of computer users, would lead to Apple’s controlling the mainstream digital-music market on all platforms for a decade or more, as its entertainment empire spread to other realms.

. . . revolutionized the telecommunications industry.

Once Apple had gotten a taste of building consumer electronics devices that were sort of like computers but way smaller and easier to use (e.g., iPods), the stage was set for another handheld device of a similar shape, one that also synced with iTunes: the Apple iPhone. Without the iPhone, there would be no Android, as a court recently ruled. Mobile-software developers would still be forced to wait through eighteen-month development-and-approval cycles for a tiny spot on a cell-phone “deck,” as the home screens used to be called. In other words: no apps, at least for much, much longer, until another company with the clout to make a phone that acted like a computer acceptable to cell-phone carriers surfaced.

. . . reinvented the tablet.

Without the iPod, there would be no iPhone. Without the iPhone, there would be no iPad. Steve Jobs thought tablets that used a stylus were silly, but once Apple had the iPhone, all it had to do to reinvent the tablet was expand the dimensions of the iPhone. As of today, according to Apple, the iPad has 68% market share among tablet users, and perhaps more important, 91% of tablet traffic to websites comes from iPads. Without the iPod, would Apple ever have gotten there? Clearly I am arguing that it would not have or, at the very least, that it would have cost Apple crucial years.

. . . been cool.

To normal people – the ones who don’t spend all day reading liveblogs – computers used to be dorky. It’s hard to believe, now that geeks are “the new rock stars” or whatever and the most famous celebrities are known as much for their Twitter feeds as for their creative output. Music, as represented by the iPod, iTunes and those iconic ads like the one pictured above, made Apple (and technology, for that matter) cool to normal people.

The iPod was not just a music player. It provided the resources for Apple to build itself into the most valuable company in the world and the marketing to make normal people care not just about this one company but about the computing industry in general. It’s probably a good thing that Steve Jobs was a music fan.